How Long Will a Fiberglass Boat Last ?

[irwinsailor]

I would like to start by saying that I am not asking for any comments on my boat! My question is with average care and use how long will a average fiberglass boat last? Are there any studies about fiberglass over the long term? Because there are few if any glass boats over 50 years I don't know how to gauge a boats life.

[Pblais]

My inclination is that the fibreglass itself is not the critical part of the boat that will fail. It's all the other stuff that seems to need a lot of work on a regular basis.

You still need to clean and paint the bottom and tend to cosmetics. Last month I was on a fibreglass boat that was 40 years old. To me it appeared to be as nice as it was way back when it was built. They work hard keeping it up - as we al do if we keep our boats in good condition.

last week I was out to the yard to see my boat and next to it was a wood 1920's boat. About 60 ft long with a a wood cabin up front and a fancy cabin in the aft for passengers. The crew was refitting it with new shatfs. The boat was a classic and will probably be fixed up and repowered yet this year. If they can do that with a boat almost 80 years old. I think a boat could last longer than I can with proper effort and money.

I'm itching to get back out on the water and see if I can wear some oif the new bottom paint off.

[irwinsailor]

I would think that you can rebuild a wood boat forever as long as you stay on top of repairs. But fiberglass I would thik will degrade at the same time. Come on Jeff! I'm sure you have some insight here.

[Jeff H]

I would not think that fiberglass has a life span per se. Neither concrete nor fiberglass truly breaks down or loses strength on their own. They require other causes. In the case of fiberglass loss of strength can result from one or more of the following,

-The surface resins will UV degrade.
-Prolonged saturation with water will affect the byproducts formed in the resin hardening process turning some into acids. These acids can break down the bond between the glass reinforcing and the resin.

-Fiberglass is prone to fatigue in areas repetitively loaded and unloaded at the point where it is repetitively deflected. High load concentration areas such as at bulkheads, hull/deck joints and keel joints are particularly prone. (see discussion on older boats below)

-Salts suspended in water will move through some of the larger capillaries within the matrix. Salts have larger molecules than water. At some point these salts cannot move further and are deposited as the water keeps moving toward an area with lower moisture content. Once dried these salt turn into a crystalline form and exert great pressure on the adjacent matrix.

-Poor construction techniques with poorly handled cloth, poorly mixed or over accelerated resins, and poor resin to fiber ratios were very typical in early fiberglass boats. These weaker areas can be actually subjected to higher stresses that result from much heavier boats. It’s not all that unusual to see small spider cracking and/or small fractures in early glass boats.

-Of course beyond the simple fiberglass degradation there is core deterioration, and the deterioration of such things as the plywood bulkheads and flats that form a part of the boat’s structure.

In a study performed by the marine insurance industry looking at claims on older boats and doing destructive testing on older hull materials, it was found that many of these earlier boats have suffered a significant loss of ductility and impact resistance. This problem is especially prevalent in heavier uncored boats constructed even as late as the 1980's before internal structural framing systems became the norm. Boats built during the early years of boat building tended to use a lot more accelerators than we use today. They also would bulk up the matrix with resin rich laminations (approaching 50/50 ratios rather than the idea 30/70) non-directional fabrics (mat or chopped glass) in order to achieve a desired hull thickness. Resin rich laminates and non-directional materials have been shown to reduce impact resistance and to increase the tendency towards fatigue. The absence of internal framing means that there is greater flexure in these older boats and that flexure increases fatigue further. Apparently, there are an increasing number of marine insurance underwriters refusing to insure older boats because of these issues.

There are probably other forms of degradation that I have not thought of but I think that the real end of the life of a boat is going to be economic. In other words the cost to maintain and repair an old boat will get to be far beyond what it is worth in the marketplace. I would guess this was the end of more wooden boats than rot. I can give you a bit of an example from land structures. When I was doing my thesis in college, I came across a government statistic, which if I remember it correctly suggested that in the years between 1948 and 1973 more houses had been built in America than in all of history before that time. In another study these houses were estimated to have a useful life span of 35 years or so. As an architect today I see a lot of thirty five year old houses that need new bathrooms, kitchens, heating systems, modern insulation, floor finishes, etc. But beyond the physical problems of these houses, tastes have changes so that today these houses in perfect shape still has proportionately small market value. With such a small market value it often does not make sense from a resale point of view to rebuild and these houses are therefore often sold for little more than land value. At some level, this drives me crazy, since we are tearing down perfectly solid structures that 35 years ago was perfectly adequate for the people who built it, but today does not meet the “modern” standards.

The same thing happens in boats. You may find a boat that has a perfectly sound hull. Perhaps it needs sails, standing and running rigging, a bit of galley updating, some minor electronics, a bit or rewiring, new plumbing, upholstery, a little deck core work, an engine rebuild, or for the big spender, replacement. Pretty soon you can buy a much newer boat with all relatively new gear for less than you’d have in the old girl. Its not hard for an old boat to suddenly be worth more as salvage than as a boat. A couple years ago a couple friends of mine were given a Rainbow in reasonable shape. She just needed sails and they wanted an auxiliary, but even buying everything used the boat was worth a lot less than the cost of the “new-used” parts. When they couldn’t afford the slip fees, the Rainbow was disposed of. She now graces a landfill and the cast iron keel was sold for scrap for more than they could sell the whole boat for.

Wooden boats represent the difference between a maintainable construction method versus a low maintenance. A wooden boat can be rebuilt for a nearly infinite period of time until it becomes a sailing equivalent of ‘George Washington’s axe’ (as in “that’s George Washington’s axe. It’s had a few new handles and a few new heads but that is still George Washington’s axe”.)

And finally if you buy an old fiberglass boat, paint the bilges white. It does nothing for the boat, but if you ever have to sell the boat, a potential buyer may look in your bilge and say “Lets buy her because any man that would love a boat so much that he went through the trouble to paint the bilge white must have enjoyed this boat and taken great care of her no matter what her age.”

Good Luck,
Jeff

[irwinsailor]

I can only wonder about one statement that you made in your post Jeff. That is about the 35 year old houses. I have never seen that happen in my area. 35 to 50 year old homes that need updating are favorites of investers here. The only houses that get razed around here that are 35 years old are houses on the lake to make room for the new multimillion dollar replacement. As for the boats you may be correct only time will tell.

[BC Mike]

If you are under 50 you might ask what is the life span of a boat. If you are over 50 you ask will this boat last as long as I will. It is a civilized society where old men plant trees, that they will never enjoy sitting in the shade of. If I do not change boats then the question for me is, will this boat last 30 years and what will be required to make it last that long. I see a new diesel, new sails, new rigging, batteries paint and so on in my future. The boat was paid for many years ago, and if I maintain it then it is more than cost effective. I have no real need to insure it for its value, but I must keep liability insurance. Let me take a stab at the actual question. A well built wooden or fiberglass boat should last 100 years with appropriate maintainence. Michael Casling

[Kevin]

Jeff,

I greatly enjoy & value your comments on various boards, but I think you might be mistaken with regard to the thoughts about salts, & molecules, & the glass matrix.

Salts, by definition, do not exist as molecules, rather they are single positively or negatively charged particles (atoms, or ions) with typical valances (charges) of + or - 1, 2, 3....in essence either they have 1, 2, or 3 extra electrons or 1, 2, or 3 too few electrons. Too many electrons = a net negative charge, too few electrons = a net positive charge. The ions themselves exist in water dissassociated from each other (no molecules) but in close electrostatic association with particles of opposite charge.

They can & surely do migrate along with water into the glass matrix & particularly into resin voids (often contributing to 'blisters'). However, the "Salts have larger molecules than water. At some point these salts cannot move further and are deposited as the water keeps moving toward an area with lower moisture content" does not happen as this would violate the Second Law of Thermodynamics. Admittedly it's been 15-16 years since P-Chem and diving into the 2nd Law, but I think I remember the basics correctly.

[GordMay]

Kevin:
I’m not certain that I understand how the 2ND Law relates to the deposition of dissolved salts out of water solution. I’d welcome further illumination.
Are you questioning the actuality of salt deposition, or merely Jeff’s description of the mechanism under which it occurs? [sorry, I’m a little dense ]
Respectfully,
Gord

[irwinsailor]

After reading all the posts I think that a fiberglass boat should have a fairly long useful life of well over 50 years. How important is doing a blister job with epoxy barier coats. Will this extend the life of most boats? I have already done this to my boat and I'm wondering if it was worth all the work.

[BC Mike]

The gelcoat is permiable or simply it leaks, that will allow water to get to the glass layup. The water may or may not cause problems. Even if the brand of boat in question has never had a blister problem, I think it is a sound idea to seal the gelcoat after it has dried. There are several paints that can do this job. Ocean Navigator in its latest addition has part one of a two part article on the subject. I used POR on the keel and the gelcoat, it was easy to apply, drys in damp weather and is very smooth when dry. Michael Casling

[irwinsailor]

I used 7 coats of WEST epoxy after a great deal of grinding, filling and fairing. I hope it was worth all the work. One guy said that it was the first racing bottom that he had seen on a cruising boat.

[BC Mike]

You deserve to sleep better at night knowing your bottom is protected. My boat also has a very smooth bottom.
Michael Casling

[delmarrey]

Irwinsailor,
So, how thick is this coat on the bottom? Did you add any glass to the coats? The reason I ask is, an epoxy coat being too thick without any internal support may start cracking when the hull flexes in the seas.

I have a couple of coupons of resins I've been experimenting with. One is polyester and the other is West’s epoxy (no glass added). Both are about 1/2" thick. I've left them out in the weather for over a year now and once in a while I'll give'm a good smack with a hammer to see which one holds up better. The polyester seems to be a bit more brittle but they both shatter. On the other hand when I cut them with a bandsaw the polyester cuts like a plastic and the epoxy chips and cracks while being cut.

So, my conclusion is that, the epoxy has a better impact strength and the polyester has better elasticity. So a flexing hull would be better made of polyester. Thin coats of epoxy would probably flex well but any significant thickness would crack.

Now on a wood/epoxy composit hull the wood would take most of the stress.

West Systems recommends 2-3 coats maybe 6 coats or 20 mil's (.020"= a matchbook cover) The larger the hull the more allowable.

Those are MY conclusions not necessarily scientific.
...................._/)

[irwinsailor]

As I recall west said to roll 5 coats. I sealed the hull and all the blister work with 2 coats of clear epoxy then rolled 5 coats of west with the aluminum oxide additive that they recomend. I do not remember what the thickness per coat is.

[delmarrey]

If West recommens all those coats who am I to disput that. From the pictures of your vessel is doesn't look like there would be much flexing. Whereas on mine I'd be a little more concerned.
I 've been working on this vessel of mine that has had 23 years of mismanagment/abuse and I can see what old repairs and lack of the proper repair comes out like. Using fillers to fare in/on corners of stress areas without any glass/reinforcement ends up with spider cracks or worse. I've seen first hand what over fill with epoxy and others looks like.

That's all............................._/)